a) A stepped optical fiber consists of a central cylindrical core of refractive index n1 and a cladding of refractive index n2. Show that the maximum acceptable angle at which light enters the plane end of the core of the fiber from air is
èmax = (sin^-1) x [(n1^2)-(n2^2)]^-1 . Assume that the refractive
index of air is n0=1.0.
b) A sharp pulse of light is launched into a stepped optical fiber of length L. If the maximum range of angles for light entering the fiber is used, show that the width of the pulse on leaving the fiber will be
Ät = [L(n1)/c] x [(n1 /n2)- 1] . Note that the width of the pulse means the difference between the longest and the shortest times of travel.
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